/*
 * =====================================================================================
 *
 *       Filename:  cpa_md5.h
 *
 *    Description:  cpa_md5 class definition.
 *
 *        Version:  1.0
 *        Created:  09/08/2018
 *       Revision:  none
 *       Compiler:  gcc
 *
 *         Author:  zhulin, shzhulin3@jd.com
 *        Company:  JD.com, Inc.
 *
 * =====================================================================================
 */


#ifndef BZF_MD5_H
#define BZF_MD5_H

#include <string>
#include <iostream>


// a small class for calculating MD5 hashes of strings or byte arrays
// it is not meant to be fast or secure
//
// usage: 1) feed it blocks of uchars with update()
//      2) finalize()
//      3) get hexdigest() string
//      or
//      MD5(std::string).hexdigest()
//
// assumes that char is 8 bit and int is 32 bit
class MD5
{
public:
  typedef unsigned int size_type; // must be 32bit

  MD5();
  MD5(const std::string& text);
  void update(const unsigned char *buf, size_type length);
  void update(const char *buf, size_type length);
  MD5& finalize();
  std::string hexdigest() const;
  std::string md5() const;
  friend std::ostream& operator<<(std::ostream&, MD5 md5);

private:
  void init();
  typedef unsigned char uint1; //  8bit
  typedef unsigned int uint4;  // 32bit
  enum {blocksize = 64}; // VC6 won't eat a const static int here

  void transform(const uint1 block[blocksize]);
  static void decode(uint4 output[], const uint1 input[], size_type len);
  static void encode(uint1 output[], const uint4 input[], size_type len);

  bool finalized;
  uint1 buffer[blocksize]; // bytes that didn't fit in last 64 byte chunk
  uint4 count[2];   // 64bit counter for number of bits (lo, hi)
  uint4 state[4];   // digest so far
  uint1 digest[16]; // the result

  // low level logic operations
  static inline uint4 F(uint4 x, uint4 y, uint4 z);
  static inline uint4 G(uint4 x, uint4 y, uint4 z);
  static inline uint4 H(uint4 x, uint4 y, uint4 z);
  static inline uint4 I(uint4 x, uint4 y, uint4 z);
  static inline uint4 rotate_left(uint4 x, int n);
  static inline void FF(uint4 &a, uint4 b, uint4 c, uint4 d, uint4 x, uint4 s, uint4 ac);
  static inline void GG(uint4 &a, uint4 b, uint4 c, uint4 d, uint4 x, uint4 s, uint4 ac);
  static inline void HH(uint4 &a, uint4 b, uint4 c, uint4 d, uint4 x, uint4 s, uint4 ac);
  static inline void II(uint4 &a, uint4 b, uint4 c, uint4 d, uint4 x, uint4 s, uint4 ac);
};

#endif
